Interpersonal heart rate synchrony predicts effective group performance in a naturalistic collective decision-making task.

Groups often outperform individuals in problem-solving. However, failure of group members to critically evaluate ideas in a discussion risks sub-optimal outcomes - a phenomenon called "groupthink". While recent studies have found interpersonal physiological synchrony to correlate with shared attention and group cohesion, whether it can track group efficacy in a collective decision-making task with an objectively defined performance measure remains controversial. To address this gap, we collected heart rate data from 58 groups (n=271) performing a task based on the hidden profile paradigm. Using multi-dimensional recurrence quantification analysis (MdRQA) and machine learning, we found that heart rate synchrony predicted the probability of groups overriding groupthink and reaching correct consensus with more than 70% cross-validation accuracy-significantly higher than that predicted by subjective assessment of team function or baseline heart rates alone. These findings demonstrate that heart rate synchrony during a naturalistic group discussion could be a biomarker of effective collective decision-making.